Igniter



Jan. 20, 1948.

c. N. HICKMAN 2,434,652

Filed March 1, 1944 3 ELARENEEN.H|EKMAN,

cfim fifmw W Patented Jan. 20, 1948 IGNITER I Clarence N. Hickman, Jackson Heights, N. Y., as

signor to United States of America, as represented by the Secretary of War Appl cation March 1, 1944. Serial No. 524,565 1 Claim. (c1. so ss.s)

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) The invention described herein may :be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to a powder igniter, more particularly to an igniter for igniting the propellant charge of a rocket projectile.

It has been previously discovered that optimum burning conditions for the propellant charge of a rocket projectile is obtained by utilizing a powder charge in the form of a stack of separate disk-like grains which are treated to restrict burning to the contiguous surfaces of such powder disks or wafers. One of the important features of the wafer stack arrangement of rocket propellant is that the burning time may be controlled by varying the web thicknessof the disks. In this manner an extremely short burning time of the propellant charge may be realized, which is an essential safety requirement when firing a rocket projectile from a shoulder launcher.

It was found however that with such arrangement of the propellant charge that it was particularly difiicult to obtain uniform ignition of the propellant grains, especially at low temperatures, with conventional igniters. The primer flame failed to penetrate between the disks so as to adequately ignite their contiguous surfaces until after ignition of the inner and outer areas of the grains had already taken place. Such non-uniform ignition is especially unsatisfactory when the length of burning time is highly critical.

Accordingly. it is an object of this invention to provide an improved igniter to ignite a charge of powder.

A further object of this invention is to provide an igniter to uniformly ignite a propellant charge of a rocket projectile comprising a stack of powder disks or wafers, and particularly to ignite the contiguous surfaces thereof.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawing in which:

Fig. 1 is a longitudinal sectional view of a a plurality of individual grains of powder,

shaped as washers, on a perforated non-combustible tube. The interior of the perforated tube is filled with a suitable ignition material, preferably black-powder, which is arranged to be ignited :by an electrically fired squib. With this arrangement the contiguous surfaces of the washers of powder can be immediately and uniformly ignited by the hot flame of the burning black powder expelled thru the perforations of the tube.

There is shown in Fig. 1 a rocket projectile embodying this invention. A hollow cylindrical rocket motor 8 is provided to house the propellant charge 2. Rocket motor I terminates in a nozzle 3 of conventional Venturi construction. Nozzle 3 maybe integrally formed with rocket motor i as shown, or may be constructed as a separate unit and screwed onto the end of rocket motor I as desired. The other end of rocket motor 9 is provided with threads 4 on the interior surface thereof to receive the threaded end of a rocket projectile head 5. The head 5 contains the pay load" (not shown) which may consist of a high explosive, a chemical grenade, or other material. A threaded axial hole 6 is provided in the base of head 5 to receive the threaded end of a perforated tube 1. Hole 9 however, does not communicate with the hollow interior of head 5.

The tube 1 is thus axially mounted within rocket motor I and extends nearly to the throat of nozzle 3 as shown in the accompanying drawing. Tube I is provided with a plurality of perforations 8. A suitable retainer'element i4 is mounted on the unsupported end of tube 1. Such retainer may comprise a plurality of fins Ma welded to tube 1, but many other forms of retainers are immediately obvious. The tube 1 is filled with a readily ignitable material 9 such as black powder preferably contained in a combustible container (not shown) such as Cellophane or paper. Black powder 9 is ignited by a conventional electrical squib III which is placed within tube l adjacent head 5 as shown in Fig. 1. Two electric lead wires II and i2 of squib it! pass thru the open end of nozzle 3 to suitable contact points on the exterior of the rocket (not shown).

Propellant charge 2 comprises a column of a plurality of powder grains preferably in the form preferably treated by any well known means to resist burning so that such surfaces will burn less readily than the contiguous surfaces of powder washers l3. For example, a solution of dimethyl-phenyl-urea, a coating of graphite or a solution of 0.1-1.0 percent of paraflln dissolved in benzine applied to these surfaces will substantially aid in resisting burning at such points.

When squib I is discharged by application of electric current to wires H and II the black powder ignition charge 9 is instantaneously ignited and the resulting flames shoot outwardly thru perforations 8 in tube 1 to ignite powder grains 13. The primer flames readily pass between the contiguous surfaces of each powder grain l3 igniting such surfaces. Thus rapid and uniform ignition of all of the powder grains [3 is readily obtained and by means of this uniform ignition of the contiguous surfaces a very 'efllcient combustion of extremely short duration is obtained.

It will be recognized that the type of igniter herein described will be equally efficient in igniting any columnar type of propellant charge whether such charge be a. bundle of powder sticks or a stack of powder disks as shown in the accompanying drawing.

I claim:

In a rocket projectile having a propulsion powder chamber and a powder charge comprising a stack of powder washers with full contact between faces, a deterrent covering the inner and outer peripheries of the washers, and an igniter comprising a hollow tube secured to the forward wall of the powder chamber and extending rearwardly therefrom, said tube arranged to pass thru the central opening of the stack of powder washers, said tube having a, plurality of spaced perforations thru the walls thereof, and an igniting charge substantially filling the interior of said tube. 4

CLARENCE N. HICKMAN.

. REFERENCES CITED The following references are of record in th file of this patent:

UNITED STATES PATENTS 

